The KeepInScreenBounds property puts back a RadWindow that is dragged out of the viewport inside, so that at least its top left corner is visible. This also goes for RadWindows that are larger than the available viewport.
Another thing I can suggest at this point is trying to force the confirm dialog to recenter after it shows:
//you can try adjusting(decreasing) this timeout
If this does not help, I advise that you post here the code for a page that will show the issue so we can have a look at the actual case.
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